Effect of intracarotid papaverine on human cerebral blood flow and vascular resistance during acute hemispheric arterial hypotension

This study assessed the feasibility of augmenting cerebral blood flow (CBF) and decreasing hemispheric cerebrovascular resistance (CVR) by intracarotid papaverine during acute cerebral hypotension. Awake patients (n = 10) undergoing transfemoral balloon occlusion of an internal carotid artery (ICA) with nitroprusside (SNP)-induced systemic hypotension (10% reduction of mean arterial pressure) were studied. We measured mean femoral artery pressure (MAP), mean distal ICA pressure (P(ica)), and CBF (intracarotid 133Xe) at two time points: before and after intracarotid papaverine infusion (1 or 7 mg/min). Two patients became symptomatic immediately after ICA occlusion and were excluded. One patient developed a focal seizure during papaverine infusion. In another, the occlusion balloon deflated prematurely. Of the remaining six patients, two of the three patients who received high-dose papaverine (7 mg/min) developed transient obtundation. The remaining three patients, who received low-dose papaverine (1 mg/min), did not develop any neurologic symptoms. There was a trend for intracarotid papaverine to increase hemispheric CBF by 36% (33 +/- 10 versus 45 +/- 22 ml x 100 g(-1) x min(-1), P = .084, n = 6); papaverine decreased CVR from 1.3 +/- 0.4 to 1.0 +/- 0.3 mm Hg x ml(-1) x 100 g(-1) x min(-1) (P = .049). There was no significant change in heart rate, MAP, or P(ica) during experimental protocol. Manipulation of CVR by intracarotid papaverine during acute hemispheric arterial hypotension appears to be feasible. Further studies are needed to establish safety and efficacy.     

Predictors and clinical implications of shivering during therapeutic normothermia

Background

Shivering during induced normothermia (IN) remains a therapeutic limitation. We investigated potential risk factors and clinical implications of shivering during IN.

Methods

Post hoc analysis was performed on 24 patients enrolled in a clinical trial of an automated surface cooling system to achieve IN. Hyponatremia was defined as serum levels <136 mmol/L and hypomagnesaemia as levels <1.5 mg/dL. Continuous heat energy transfer (kcal/h) was averaged hourly. Glasgow Coma Scale (GCS) scores were recorded every 2 h. Shivering status was documented hourly. Mixed effects modeling was used to determine clinical measures associated with shivering. Generalized estimating equation (GEE) models were used to compare baseline-adjusted repeated-measures GCS scores.

Results

About of 24 (39%) patients demonstrated shivering. Shivering was associated with men (67% vs. 21%, P = 0.03), hyponatremia (44% vs. 7%, P = 0.03), and hypomagnesaemia (56% vs. 7%, P = 0.02). The average kcal/h (158 ± 645 kcal/h vs. 493 ± 645 kcal/h, P = 0.03) was greater in shivering patients. Shivering was positively associated with increases in heart rate (P < 0.001), respiratory rate (P < 0.001), and kcal/h (P < 0.001). Non-shivering patients showed a greater increase from baseline GCS (GEE, P = 0.02) at 24 h. No differences in sedative doses or fever burden were noted between shiverers and non-shiverers.

Conclusions

Men, hyponatremia, and hypomagnesaemia may predispose febrile patients treated with IN to shivering. Shivering dramatically increases the amount of heat transfer required to maintain normothermia, and may be associated with adverse effects on level of consciousness.     

Trying versus liking fruits and vegetables: correspondence between mothers and preschoolers

Extensive research indicates that a diet rich in fruits and vegetables (F&V) protects against numerous illnesses in adulthood, but that most individuals, including children, consume far fewer F&V per day than is recommended. Since evidence suggests that eating habits in childhood track into adulthood, more research is necessary to learn about how parental F&V intake and opportunities influence child F&V consumption. The purpose of this study was to examine the relationship between mothers' F&V preferences and those of their preschool-age children to determine if greater maternal "liking" of fruits and vegetables was associated with their reports of their children's "trying" more fruits and vegetables. Eighty-three mothers completed a questionnaire that assessed whether they and their preschoolers had tried or liked a variety of F&V. Mothers liked 86% of the fruits they tried, girls 76%, and boys 69%. Mothers liked 81% of the vegetables they tried; boys and girls liked 55%. Mothers' likes correlated with F&V that their children tried, but mothers' likes also limited the number of F&V that their children tried. Mothers reported preferences for F&V are associated with estimates of their preschoolers' preferences for F&V. Relative to girls, boys may need additional opportunities for F&V exposure.     

Effect of acute physiologic derangements on outcome after subarachnoid hemorrhage

OBJECTIVE: To determine the effect that acute physiologic derangements have on outcome after subarachnoid hemorrhage (SAH) and to design a composite score summarizing these abnormalities. DESIGN: Prospective observational study. SETTING: Neuroscience intensive care unit in a tertiary care academic center. PATIENTS: Consecutive cohort of 413 patients with SAH admitted within 3 days of SAH onset with 3-month modified Rankin Scale scores. INTERVENTIONS: None. RESULTS: Among 20 physiologic variables assessed within 24 hrs of admission, four were independently associated with death or severe disability (modified Rankin Scale score, 4-6) at 3 months in a multivariate analysis: arterio-alveolar gradient of >125 mm Hg (odds ratio [OR], 4.5; 95% confidence interval [CI], 2.7-7.6), serum bicarbonate of <20 mmol/L (OR, 2.9; 95% CI, 1.6-5.6), serum glucose of >180 mg/dL (OR, 2.8; 95% CI, 1.6-4.8), and mean arterial pressure of <70 or >130 mm Hg (OR, 1.7; 95% CI, 1.0-2.9). Based on their proportional contribution to outcome, we constructed the SAH Physiologic Derangement Score (SAH-PDS; range, 0-8) by assigning the following weights for abnormal findings: arterio-alveolar gradient, 3 points; bicarbonate, 2 points; glucose, 2 points; and mean arterial pressure, 1 point. After controlling for known predictors of death or severe disability (age, admission neurologic status, loss of consciousness, aneurysm size, intraventricular hemorrhage, and rebleeding), the SAH Physiologic Derangement Score was independently associated with poor outcome (OR, 1.3 for each point increase; 95% CI, 1.1-1.6). By contrast, the systemic inflammatory response syndrome score and the Acute Physiology and Chronic Health Evaluation II physiologic subscore did not add predictive value to the model. CONCLUSION: Acute interventions specifically targeting hypoxemia, metabolic acidosis, hyperglycemia, and cardiovascular instability may improve the outcome of SAH patients. The SAH Physiologic Derangement Score may prove useful for rapidly quantifying the severity of important physiologic derangements in acute SAH.     

Pharmacodynamics and Pharmacokinetics of Cisatracurium in Geriatric Surgical Patients

Background: Cisatracurium, one of ten stereoisomers that comprise atracurium, is more potent than atracurium and has less propensity to release histamine. This study compares the pharmacokinetics and pharmacodynamics of cisatracurium in elderly and young patients.

Methods: Twelve elderly (aged 65-82 yr) and 12 younger patients (aged 30-49 yr) were anesthetized with nitrous oxide, fentanyl, and isoflurane (0.7%, end-tidal). The mechanomyographic response to train-of-four stimulation was assessed every 15 s after the administration of cisatracurium (0.1 mg/kg). Arterial samples were obtained over 6 h. Plasma cisatracurium concentration versus time data were fit to compartmental models. Pharmacokinetic parameters were determined assuming that elimination occurred from the central compartment only. This provides accurate clearance and half-life estimates but underestimates Vss (reported herein as Vss '). The pharmacodynamic response was described by the neuromuscular blocking profile.

Results: Onset to 90% paralysis (mean+/-SD) was delayed in the elderly (3.4+/-1.0 vs. 2.5+/-0.6 min). Recovery profiles were the same for both groups. Elimination half-life was minimally prolonged in the elderly (25.5+/-3.7 vs. 21.5 +/-2.4 min). The Vss ' was larger in the elderly (126 +/-16 vs. 108+/-13 ml/kg), although the clearances were the same for the two groups (5.0+/-0.9 vs. 4.6+/-0.8 ml *symbol* kg sup -1 *symbol* min sup -1).     

Cerebral blood flow reactivity to changes in carbon dioxide calculated using end-tidal versus arterial tensions

We retrospectively examined arerial and end-tidal estimations of CO2 tension used to calculate cerebrovascular reactivity in 68 anesthetized patients. CBF was measured using the intravenous 133Xe technique at mean +/- SD PaCO2 values of 28.2 +/- 5.2 and 38.8 +/- 4.8 mm Hg. The correlation between all PaCO2 and end-tidal PCO2 (PetCO2) values was y = 0.85x - 0.49 (r = 0.93, p = 0.0001). There was a moderate correlation between age and the difference between PaCO2 and PetCO2 (y = 0.11x + 0.79; r = 0.73, p = 0.0001). Cerebrovascular reactivity to changes in CO2 (ml 100 g-1 min-1 mm Hg-1) was similar (p = 0.358) when calculated by using either PaCO2 (1.9 +/- 0.8) or PetCO2 (1.8 +/- 0.8) and highly correlated (y = 0.86x + 0.23; r = 0.91, p = 0.0001). The CBF response to changes in CO2 tension can be reliably estimated from noninvasive measurement of PetCO2.